A phrase used to describe the action of: pulling into a parking spot, taking a turn, or just driving in general all at an extreme, and reckless rate of speed. One must announced that he/she is comin in hot! in order to actually be classified as Coming in hot.

Josh: Look out boys we're coming in hot!
Brandon: Why? Is there a 'Nader after you?
Kyle: Oh noes you hit granny!

To arrive at a point/location in an uncontrolled manner and often with excessive speed. In certain situations, this can also involve the use of a weapon of some sort.

Guy A: James made an ass of himself at Dick's party last night.
Guy B: Why's that?
Guy A: Ahh, he saw this group of hott females and decided he wanted to make a go at them.
Guy B: Yeah.
Guy A: Well, he got so geeked up that he ended up coming in hot, knocked over a bunch of shit, and pissed the girls off. They cursed him out and left the scene.

The S.W.A.T. team was coming in hot as they put several bullets into each one of our hostage takers, as well as an innocent bystander. Hey, at least it wasn't me.